In the field of tracking and navigation, it may be desirable to estimate orientation with respect to the Earth. Global positioning system (GPS) technology, for example, relies on external signals from multiple satellites to triangulate a solution for an approximate position. With limited accuracy and/or availability, GPS may not be suitable for some highly precise applications of navigation or tracking, such as, for example, determining precise azimuth, and may at times be unavailable due to various circumstances such as blocked, distorted, or otherwise unavailable signals.
One possible way to overcome the unavailability of external aiding sources such as GPS is the use of instrumentation that measures the strength and direction of naturally occurring magnetic fields, such as a magnetometer. Magnetometers may be used for tracking and navigation, and among other things, making azimuth measurements by measuring the weak magnetic field of the Earth. However, magnetometers are prone to error sources such as ferrous metallic objects or strong electric currents that can cause strong magnetic field distortions.
To this end, it may be desirable to provide a system that enables the determination of the orientation of a body to the Earth using sources other than GPS and/or magnetometers. Orientation may be relative to true north, or azimuth, and may include, for example, latitude, longitude, and/or measurements for bank angle and elevation angle with respect to a reference surface of the Earth.
It may also be desirable to determine with the azimuth, bank angle, and/or elevation of a stationary fixture with respect to the Earth using observations of celestial bodies, such as, for example, the Sun, the moon, stars, and/or planets. Further, it may be desirable to use detectable celestial bodies to determine the position and/or attitude of an object remote from a location of a stationary fixture, by determining any one or more of the longitude, latitude, azimuth, and/or elevation angle of the remote object with respect to the Earth or with respect to celestial bodies.
It may also be desirable to provide a system that determines the orientation of a fixture relative to the Earth, and determines the position, attitude, and/or heading using detectable celestial bodies. For example, a vehicle may use detectable celestial bodies to determine any one or more of longitude, latitude, azimuth, elevation angle, and/or bank angle of a vehicle at rest. It may also be desirable to provide a system and method for aiding navigation of a vehicle during travel.